WO-A-90 07 308 discloses a jaw implant comprising a carrier and a biocompatible diaphragm covering the carrier. The carrier has a central portion with a threaded bore for the attachment of an artificial substitute tooth. The diaphragm is connected to the carrier during insertion of the carrier into a hole in a jawbone so that it covers the area of the jawbone surrounding the carrier and protects it against the growing in of the gingival bindweb and the epithelium tissue, as well as against the penetration of microorganisms. The amount of jawbone available for insertion of such implants however can be so small that an adequate anchoring of the previously described implant is no longer possible. This problem frequently occurs with implants into the upper jaw.
In addition to such implants, implants for attaching substitute tooth are generally known comprising hollow cylindrical sockets provided with apertures and a single piece head portion widening away from the socket. When a substitute tooth is to be fastened with the head portion at a jawbone, the implant is inserted into a hole of the jawbone so that it is approximately flush or above the surface of the jawbone. The bore in the end side of the head portion is then closed off with a sealing screw. The implant now remains in this sealed state in the jawbone during the healing phase, which may, for instance, last for several months. The bone tissue grows during this healing phase into the cylindrical socket which is tightly anchored in the jawbone. The sealing or closing screw is subsequently removed and a secondary element is threaded into the implant. The secondary element forms a post or pillar at which the artificial substitute tooth or denture is fastened.
During the healing phase, the epithelium tissue and the gingival bindweb or connective tissue normally grows faster than the bone tissue of the alveolar extension and especially faster than the cement and the bone cells forming the desmodontal bindweb. After insertion of an implant, the epithelium tissue and the gingival bindweb grow into the gap between the jawbone and the implant and deposit themselves at the implant, whereby the growing-together of the bone tissue and the implant is delayed or even entirely prevented. Such methods however permit microorganisms to penetrate from the mouth cavity into the existing gaps and cause infections.
The problems with such previously known devices were hitherto solved in two different ways. According to one way, bone shavings obtained by a surgical intervention into the pelvic region or portions of ribs of the patient were used for thickening the jawbone. After the jawbone is thickened, one of the known implants is inserted into the intended area of the jawbone. Experiments have shown however that such intervention is very complicated, not always successful and assumes that the transplanted bone tissue grows completely together with the jawbone and the implant. The other type of treatment involves the insertion of an implant into the jawbone, increase and thickening of the bone tissue of the alveolar extension and the cement. In this type of treatment, the bone cells forming the desmodontal bindweb are promoted in a targeted manner. Cells forming this tissue can multiply at the jawbone, if it is isolated from the gingival bindweb during the bone regeneration phase. The isolation can be achieved by using a biocompatible diaphragm between the gingival bindweb and the bone tissue. Such a diaphragm would have pores permitting the passage of gases through the diaphragm and/or the deposition of cells and the growing of such cells into the diaphragm. After bone formation, one of the already known implants could be inserted into the jawbone. Such treatment however has the distinct disadvantage of having at least three chronologically separate operations which makes the entire treatment period approximately twice as long as with a normal implant. The danger of a failure is correspondingly increased.
It is therefore an object of the present invention to provide an implant that has a relatively short treatment period.
Another object of the invention is to provide an implant which permits adequate anchoring to a jawbone or the like.
Still another object of the present invention is to provide a safe implant which additionally prevents the entry of microorganisms from the mouth cavity and into the existing gaps.
Additionally, an object of the invention is to provide an implant which is particularly helpful if the jawbone area to be treated is insufficient for fixing previously known implants.
Yet another object of the invention is to provide an implant which can be replaced upon the jawbone area to be treated without prior bone formation treatment.